/****************************************************************************
 *
 * Copyright 2019 Samsung Electronics All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 *
 ****************************************************************************/
/****************************************************************************
 * libc/symtab/symtab_findorderedbyname.c
 *
 *   Copyright (C) 2009, 2014-2015 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <tinyara/config.h>

#include <string.h>
#include <debug.h>
#include <assert.h>
#include <errno.h>

#include <tinyara/symtab.h>

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: symtab_findorderedbyname
 *
 * Description:
 *   Find the symbol in the symbol table with the matching name.
 *   This version assumes that table ordered with respect to symbol name.
 *
 *   This function is a lot larger than symbtab_findbyname().  This function
 *   not be used, unless the symbol table is large and the performance
 *   benefit is worth the increased size.
 *
 * Returned Value:
 *   A reference to the symbol table entry if an entry with the matching
 *   name is found; NULL is returned if the entry is not found.
 *
 ****************************************************************************/

FAR const struct symtab_s *symtab_findorderedbyname(FAR const struct symtab_s *symtab, FAR const char *name, int nsyms)
{
	int low = 0;
	int high = nsyms - 1;
	int mid;
	int cmp;

	/* Loop until the range has been isolated to a single symbol table
	 * entry that may or may not match the search name.
	 */

	DEBUGASSERT(symtab != NULL && name != NULL);
	while (low < high) {
		/* Compare the name to the one in the middle.  (or just below
		 * the middle in the case where one is even and one is odd).
		 */

		mid = (low + high) >> 1;
		cmp = strcmp(name, symtab[mid].sym_name);
		if (cmp < 0) {
			/* name < symtab[mid].sym_name
			 *
			 * NOTE: Because of truncation in the calculation of 'mid'.
			 * 'mid' could be equal to 'low'
			 */

			high = mid > low ? mid - 1 : low;
		} else if (cmp > 0) {
			/* name > symtab[mid].sym_name */

			low = mid + 1;
		} else {
			/* symtab[mid].sym_name == name */

			return &symtab[mid];
		}
	}

	/* low == high... One final check.  We might not have actually tested
	 * the final symtab[] name.
	 *
	 *   Example: Only the last pass through loop, suppose low = 1, high = 2,
	 *   mid = 1, and symtab[high].sym_name == name.  Then we would get here with
	 *   low = 2, high = 2, but symtab[2].sym_name was never tested.
	 */

	return strcmp(name, symtab[low].sym_name) == 0 ? &symtab[low] : NULL;
}
